Abstract:Collision efficiency as an important parameter should not be ignored, and mainly depends on the real-time environment parameters such as wind velocity, water droplet diameter, temperature, humidity, atmospheric pressure and conductor diameter. Though median volume diameter (MVD) as a representative water droplet size parameters is often used to approximate the whole droplet size spectrum, however, as for different volume fraction of droplet size distribution, great relative error is between the calculated collision efficiency and real collision efficiency. A novel volume weighted diameter (VWD) is proposed to approximate the water droplet size spectrum, and the results are compared with those using the median volume diameter and the entire droplet size spectrum. The results show that this parameterization provides a more stable approximation than the median volume diameter when the collision efficiency changes. And then, the mathematic explanation is given to the higher precision based on VWD, and the application range of this method is discussed. In addition, the calculated collision efficiency is compared with measured value based on lab tests, the smaller relative error and good approximate icing mass have proved the reliability of the proposed method, and is also applied to predict the icing thickness of the practical transmission line.